Method and apparatus for transmitting and receiving data

ABSTRACT

An apparatus and method are provided for receiving data by a first transceiver. The method includes receiving information for at least one transmission mode through higher layer signaling from a second transceiver; and receiving data on a first sub-frame based on a first demodulation reference signal (DMRS), if the at least one transmission mode is transmission mode 9 or transmission mode 10 and the first sub-frame is a multimedia broadcast multicast service single frequency network (MBSFN) sub-frame.

PRIORITY

This application is a continuation of U.S. Ser. No. 13/267,402, whichwas filed in the U.S. Patent and Trademark Office on Oct. 6, 2011, andclaims priority under 35 U.S.C. § 119(a) to an application filed in theKorean Intellectual Property Office on Oct. 6, 2010, and assigned SerialNo. 10-2010-0097291, the content of each of which is incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method and an apparatus fortransmitting and receiving data, and more particularly, to transmittingand receiving data in a 3^(rd) Generation Partnership Project (3GPP)Long Term Evolution (LTE) system and an LTE Advance (LTE-A) system.

2. Description of the Related Art

In addition to providing a voice based initial service, a mobilecommunication system has evolved into a high speed and high qualitywireless packet data communication system to provide a data service anda multi-media service. Various mobile communication standards such asHigh Speed Packet Access (HSPA) and LTE of 3GPP, High Rate Packet Data(HRPD), Ultra Mobile Broadband (UMB) of 3GPP2, and 802.16e of IEEE havebeen developed to support a high speed and high quality wireless packetdata transmission service.

The newest mobile communication system uses an Adaptive Modulation andCoding (AMC) scheme and a channel response scheduling scheme to improvetransmission efficiency. When using the AMC scheme, a transmitter mayadjust an amount of data to be transmitted according to a channel state.That is, the newest mobile communication system may efficiently transmita large amount of information in such a manner that the transmitterincreases and reduces the amount of data to be transmitted to obtain areception error probability of a desired level when a channel state isexcellent and poor, respectively. When using the channel responsescheduling scheme, because the transmitter selectively provides aservice to a receiver having an excellent channel state among aplurality of receivers, system capacity is increased compared to whenthe transmitter provides a service after allotting a channel to onereceiver.

For example, the AMC scheme and the channel response scheduling schemereceive feedback of partial Channel State Information (CSI) from areceiver, and apply suitable modulation and encoding techniques at themost efficient determining time point. The AMC scheme and the channelresponse scheduling schemes are techniques that may improve transmissionefficiency in a state that a transmitter acquires sufficient informationon a transmission channel. As in a Frequency Division Duplexing (FDD)scheme, when a transmitter does not recognize a state of a transmissionchannel through a receiving channel, a receiver is designed to reportinformation about a transmission channel to the transmitter. Meanwhile,in the Time Division Duplexing (TDD) scheme, the receiver may not reportinformation about a transmission channel to the transmitter using acharacteristic capable of recognizing a state of the transmissionchannel through a receiving channel.

In recent years, research for changing a Code Division Multiple Access(CDMA) scheme being a multiple access scheme used in 2^(nd) GenerationPartnership Project (2G) and 2G mobile communication systems from a nextgeneration system to Orthogonal Frequency Division Multiple Access(OFDMA) has been actively performed. Standard organizations such as3GPP, 3GPP2, and IEEE are attempting standardization with respect to anevolution system using an OFDM or a modified OFDMA, because capacity maybe increased in the OFDMA scheme in comparison with the CDMA scheme. Oneof various factors increasing capacity in the OFDMA scheme is to performFrequency Domain Scheduling in a frequency axis. As a capacity gain maybe obtained through a channel response scheduling scheme according to achannel changing according to time, a greater capacity gain may beobtained when a channel changes according to frequency.

An LTE system uses an OFDMA scheme in a Downlink (DK) and a SingleCarrier Frequency Division Multiple Access (SC-FDMA) scheme in an Uplink(UL), and the two schemes involve performing scheduling in a frequencyaxis.

Meanwhile, a DL of the LTE system supports multiple antennatransmission. A transmitter of the LTE system may include one, two, orfour transmission antennae. When the transmitter includes a plurality oftransmission antennae, it applies pre-coding to obtain a beam forminggain and a spatial multiplexing gain. In the LTE system, a receivertransmits a Common Reference Signal (CRS) for each transmission antennato estimate a channel response from each transmission antenna. Whenadaptive pre-coding is applied to data transmission, a transmitterreports to the receiver to which pre-coding is applied, through acontrol channel.

A DL of the LTE-A system increases the number of transmission antennaeof a transmitter to support a maximum of eight transmission antennae. Ifthe number of the transmission antennae increases, the transmitter mayfurther improve the beam forming gain and the spatial multiplexing gain.However, so as to support the maximum eight transmission antennae, theamount of CRS for estimating a channel state from each transmissionantenna is increased. In the LTE-A system, to prevent rapid increase ina rate of the CRS due to the increase in the number of transmissionantennae, a receiver uses referring CSI-RS to create CSI feedbackinformation and referring Demodulation-RS (DM-RS) for data demodulation.In the LTE-A system, a newly applied transmission scheme uses CSI-RS andDM-RS. However, to maintain backward compatibility, an LTE-A transmittershould also transmit CRS.

The LTE-A system supports Multimedia Broadcast Multicast Service SingleFrequency Network (MBSFN) transmission, which spreads a service zone ofbroadcasting by transmitting the same broadcasting signal from multiplecells. The MBSFN transmission regulates to transmit the same RS frommultiple cells such that a receiver may perform coherence modulation forthe simultaneously transmitted signal without cell separation. That is,because the MBSFN cannot be supported with the CRS defined by cells,only an MBSFN dedicated RS is defined in an MBSFN sub-frame and istransmitted. Further, because a unicast service is not supported in theMBSFN sub-frame, the CRS is not transmitted.

The LTE system regulates a plurality of transmission modes to select asuitable transmission scheme according to a state of a receiver, anduses a CRS and a transmission scheme using a Dedicated Reference Signal(DRS) for channel estimation for demodulation. The LTE-A system adds atransmission scheme using DM-RS for channel estimation for demodulation.A receiver of the LTE-A system should be able to receive all of CRS,DRS, and DM-RS in consideration of backward compatibility.

The receiver of the LTE-A system may also receive a unicast service froman MBSFN sub-frame. The DM-RS may be transmitted to an MBSFN sub-frameinstead of the CRS because the MBSFN sub-frame is regarded as a sourcewithout backward compatibility. Herein, in order to distinguish from anMBSFN sub-frame set for supporting an MBSFN service, a sub-frame set forsupporting a unicast service to an MBSFN sub-frame is referred to as anLTE-A sub-frame.

In the foregoing LTE-A system, an operation of a receiver for receivinga unicast service in the MBSFN sub-frame should be defined. When areceiver of the LTE-A system is set to a transmission mode using a CRSfor demodulation, it may receive data in a general sub-frame. However,since the CRS is transmitted in the MBSFN sub-frame, although thereceiver of the LTE-A system may perform reception using DM-RS, thereceiver cannot receive data.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problems, andan aspect of the present invention is to provide a method and anapparatus for transmitting and receiving data that defines atransmission technique control method such that a transmitter of anLTE-A system may support an existing transmission scheme based on CRS ina normal sub-frame, and a receiver of an LTE-A system may receive datain an LTE-A sub-frame and be set to use the existing transmission schemebased on CRS.

In accordance with an aspect of the present invention, a method isprovided for receiving data by a first transceiver. The method includesreceiving information for at least one transmission mode through higherlayer signaling from a second transceiver; and receiving data on a firstsub-frame based on a first demodulation reference signal (DMRS), if theat least one transmission mode is transmission mode 9 or transmissionmode 10 and the first sub-frame is a multimedia broadcast multicastservice single frequency network (MBSFN) sub-frame.

In accordance with another aspect of the present invention, a method isprovided for transmitting data by a first transceiver. The methodincludes transmitting information for at least one transmission modethrough higher layer signaling to a second transceiver; and transmittingdata on a first sub-frame based on a first demodulation reference signal(DMRS), if the at least one transmission mode is transmission mode 9 ortransmission mode 10 and the first sub-frame is a multimedia broadcastmulticast service single frequency network (MBSFN) sub-frame.

In accordance with another aspect of the present invention, an apparatusis provided for receiving data. The apparatus includes a transceiver;and a controller configured to receive, via the transceiver, informationfor at least one transmission mode through higher layer signaling fromanother apparatus and to receive, via the transceiver, data on a firstsub-frame based on a first demodulation reference signal (DMRS), if theat least one transmission mode is transmission mode 9 or transmissionmode 10 and the first sub-frame is a multimedia broadcast multicastservice single frequency network (MBSFN) sub-frame.

In accordance with another aspect of the present invention, an apparatusis provided for transmitting data. The apparatus includes a transceiver;and a controller configured to transmit, via the transceiver,information for at least one transmission mode through higher layersignaling to another apparatus, and to transmit, via the transceiver,data on a first sub-frame based on a first demodulation reference signal(DMRS), if the at least one transmission mode is transmission mode 9 ortransmission mode 10 and the first sub-frame is a multimedia broadcastmulticast service single frequency network (MBSFN) sub-frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the present invention will bemore apparent from the following detailed description in conjunctionwith the accompanying drawings, in which:

FIG. 1 illustrates a downlink transmitting apparatus using a CRS of atransmitter in an LTE system according to the present invention;

FIG. 2 illustrates a downlink transmitting apparatus using a DRS of atransmitter in an LTE system according to the present invention;

FIG. 3 illustrates an example of downlink resource mapping in an LTEsystem according to the present invention;

FIG. 4 illustrates TDD of an MBSFN sub-frame;

FIG. 5 illustrates TDD of an LTE-A sub-frame;

FIG. 6 illustrates a structure of a transmitter according to the presentinvention;

FIG. 7 illustrates a structure of a receiver according to the presentinvention;

FIG. 8 illustrates a method for using a reference signal by a receiveraccording to a first, third, or fourth embodiment of the presentinvention;

FIG. 9 illustrates a method for using a reference signal by a receiveraccording to a second embodiment of the present invention; and

FIG. 10 illustrates a method for using a reference signal by a receiveraccording to a fifth embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Embodiments of the present invention are described in detail withreference to the accompanying drawings. The same reference numbers areused throughout the drawings to refer to the same or like parts.Detailed descriptions of well-known functions and structuresincorporated herein may be omitted for the sake of clarity andconciseness.

The term “Reference Signal (hereinafter RS) herein indicates a signalpreviously defined in a transmitter and a receiver for two objects. Thefirst object is to measure a CSI for the transmitter by the receiver.That is, to support an AMC, the transmitter should receive report of aCSI from the receiver, and the receiver may measure the CSI through theRS. The second object is to estimate a channel response for demodulatinga signal received by the receiver. For example, when the transmittertransmits a complex signal, the receiver should be able to estimate howa transmission signal is distorted on a channel for coherentdemodulation. That is, the receiver may estimate the channel responsewhen receiving the RS.

The LTE system defines an RS used in common in various receivers in a DLcell. This RS is referred to as a Common RS (hereinafter CRS). Since theCRS is defined differently by cells, it is a cell-specific RS. When thetransmitter transmits a signal through a multiple transmission antenna,the CRS is orthogonally designed by transmission antennae. For example,there are two antennae, and the transmitter defines and transmits twoorthogonal CRSs through respective transmission antennae.

FIG. 1 illustrates a downlink transmitting apparatus using a CRS of atransmitter in an LTE system according to the present invention. In FIG.1, the transmitter includes two transmission antennae. However, thepresent invention is not limited thereto. That is, the same explanationsare applicable to when the transmitter includes more than twotransmission antennae.

Referring to FIG. 1, a transmitter 100 includes a pre-coder 103, a firstMUltipleXer (MUX) 109 a, a second multiplexer 109 b, a firsttransmission antenna 111 a, and a second transmission antenna 111 b. Thetransmitter 100 multiplexes data signals 101 according first and secondCRSs 107 a and 107 b, and transmits the multiplexed signal.

When the pre-coder 103 receives the data signals 101 for a receiver (notshown), it shapes a beam of the data signals 101, which are configuredby one or a plurality of layers. When the data signals are configured byone layer, pre-coding corresponds to general beam-shaping. When the datasignals 100 are configured by a plurality of layers, the pre-coding isbeam-shaped by layers of the data signals 101 for spatial multiplexing.

Pre-coded signals 105 are transmitted to the first multiplexer 109 a andthe second multiplexer 109 b through a processing path. When thepre-coded signals 105 and a first CRS 107 a are input to the firstmultiplexer 109 a, the first multiplexer 109 a multiplexes the pre-codedsignals 105 according the first CRS 107 a, and transmits the multiplexedsignal through a first transmission antenna 111 a. When the pre-codedsignals 105 and a second CRS 107 b are input to the second multiplexer109 b, the second multiplexer 109 b multiplexes the pre-coded signals105 according to the second CRS 107 b, and transmits the multiplexedsignal through a second transmission antenna 111 b.

In DL transmission using the first and second CRSs 107 a and 107 b, thedata signals 101 are pre-coded, whereas the first and second CRSs 107 aand 107 b are not pre-coded. A receiver may measure a CSI that is notpre-coded through the first and second CRSs 107 a and 107 b, and thereceiver directly reports the CSI or the most preferential transmissionscheme in a given channel situation to the transmitter 100.

The LTE system defines feedback information to be reported to atransmitter in a preferential transmission scheme. A Channel QualityIndicator (CQI), a Pre-coding Matrix Indicator (PMI), and a RankIndicator (RI) are feedback information defined to support DLtransmission in the LTE system. The CQI, the PMI, and the RI indicatemodulation and coding schemes capable of being received in respectivegiven channels, the most preferential pre-coding scheme, and the numberof spatial multiplexing layers capable of being received, respectively.

However, when reporting the CQI, the PMI, and the RI, because a receiveruses a pre-coding scheme defined in a pre-coding codebook introduced ina standard, the pre-coding scheme is restrictive. For example, areceiver selects and reports the most preferential one of pre-codingmatrices to a transmitter, and the transmitter selects a pre-codingscheme from a pre-coding codebook based on the information and appliesthe selected pre-coding scheme to actual transmission. Accordingly, thetransmitter may not apply pre-coding not defined in the pre-codingcodebook. For this reason, the LTE system includes information on apre-coding scheme used in data signals in Downlink Control Information(hereinafter DCI).

The LTE-A system allows a transmitter to apply non-defined pre-coding ina pre-coding codebook. This scheme advantageously allows the transmitterto optionally determine a pre-coding scheme. Thus, a conventional CRSbased transmission scheme cannot be used. That is, because the number ofpre-coding schemes is infinite, it cannot inform the pre-coding schemeusing DCI. Accordingly, the LTE system introduces a reference signal byreceivers, namely, a Dedicated RS (DRS) for transmission of only onelayer, and the same pre-coding scheme in the data signal is applied tothe DRS. Thus, although an applied pre-coding scheme using DCI is notinformed, a receiver may estimate a pre-coded channel through DRS todemodulate a pre-coded data signal. The LTE system introduces DM-RS fromrelease-9 to extend the transmission to two layers. The LTE-A systemdefines eight DM-RSs to support transmission of a maximum eight layers.Although the same pre-coding scheme in the data signal is applied to theDM-RS and an applied pre-coding scheme using DCI is not informed, thereceiver may estimate a pre-coded channel through DM-RS to demodulate apre-coded data signal.

FIG. 2 illustrates a downlink transmitting apparatus using a DRS of atransmitter in an LTE system according to the present invention. In FIG.2, the transmitter includes two transmission antennae. However, thepresent invention is not limited thereto. That is, the same explanationsare applicable to when the transmitter includes more than twotransmission antennae. Moreover, although application of the DRS islimited to transmission of one layer in the LTE system, the DRS conceptis applicable to spatial multiplexing configuring and transmitting amaximum eight layers in the LTE-A system.

Referring to FIG. 2, a transmitter 120 includes a multiplexer 125, apre-coder 127, a first transmission antenna 131 a, and a secondtransmission antenna 131 b. The transmitter 120 multiplexes andpre-codes data signals 121 according to a DRS 123, and transmits themultiplexed and pre-coded signal.

When the data signals 121 for a receiver (not shown) and the DRS 123 areinput to the multiplexer 125, it multiplexes the data signals 121according to the DRS 123, and transfers the multiplexed signal to thepre-coder 127, which creates a pre-coded signal 129 and transmits thesignal through the first transmission antenna 131 a and the secondtransmission antenna 131 b. The pre-coded signal 129 contains the datasignal 121 and the DRS 123. A receiver may estimate a channel of thedata signals 121 based on the DRS 123 to estimate a pre-coded channelresponse reflecting both of a pre-coding scheme and a channel responseof the DRS 123.

FIG. 3 illustrates an example of downlink resource mapping in an LTEsystem according to the present invention. It is assumed that a DLresource is implemented by a normal Cyclic Prefix (CP) sub-framestructure. However, the present invention is not limited thereto. Thatis, the DL resource may be implemented by an Extended CP sub-framestructure.

Referring to FIG. 3, a smallest resource unit in a time axis is an OFDMsymbol 201. One slot 203 is configured by seven OFDM symbols 201, andone sub-frame 205 is configured by two slots 203. The sub-frame 205becomes a basic unit of resource allotment in a time axis. Head One,two, or three OFDM symbols 201 in one sub-frame 205 are used as acontrol channel region, and remaining OFDM symbols 201 are used as adata channel region. A smallest resource unit in a frequency axis is asub-carrier 207. One Resource Block (RB) 211 is configured by twelvesub-carriers. The RB 211 becomes a basic unit of resource allotment in afrequency axis. Through this, one sub-carrier 207 in a frequency axis,one OFDM symbol 201 in a time axis, and one antenna port (not shown) ina spatial axis are configured by a Resource Element (RE) 209 being thesmallest unit of a resource, and one modulation symbol is transmittedand received as an RE 209.

For example, there are four transmission antennae of a transmitter,namely, four antenna ports, and the transmitter defines and transmitsCRSs 220, 221, 222, and 223 for respective antenna ports. That is, inorder for a receiver to estimate channels of antenna ports 0, 1, 2, and3, the transmitter transmits a CRS0 (220) for antenna port 0, a CRS1(221) for antenna port 1, CRS2 (222) for antenna port 2, and a CRS3(223) for antenna port 3. The transmitter separates and transmits theCRS0 (220), the CRS1 (221), the CRS2 (222), and CRS3 (223) to differentREs 209. Through this, the CRS0 (220), the CRS1 (221), the CRS2 (222),and CRS3 (223) have characteristics that are orthogonal to each other.Moreover, the transmitter transmits a control channel signal 225 and adata channel signal 227 of data signals to an RE 209 of a controlchannel region, and an RE 209 of a data channel region, respectively. Todefine locations of the CRSs 220, 221, 222, 223 differently by cells,offsets 213 by cells may determined differently according to cellidentification.

In the LTE system, the transmitter may transmit data signals and areference signal according to a transmission mode (tm, as shown in Table1 below). Table 1 lists available transmission modes in a DL of the LTEsystem. Two types of data transmission schemes are supported in eachtransmission mode. A reference transmission scheme is allowable in acorresponding transmission mode, and a substitute transmission scheme isallowable in all transmission modes in common.

The LTE system supports various reference transmission schemes but doesnot allow a user to freely select all reference transmission schemesevery transmission time. Respective reference transmission schemesrequire different DCIs, and a receiver should previously know to receiveany DCI. Accordingly, if a transmitter sets a certain commontransmission mode to one receiver, a corresponding receiver performs areception operation in a reference transmission scheme of acorresponding common transmission mode. Because the common transmissionmode is set through higher layer signaling, time delay may not beavoided in the setting procedure.

If a reference transmission scheme of a common transmission mode set ina certain receiver no longer has a valid channel state, there is a needfor a substitute transmission scheme for changing a common transmissionmode of a corresponding receiver. Because transmission diversity is mostinsensitive to channel variation among various reference transmissionschemes, the transmission diversity is defined as a substitutetransmission scheme with respect to seven types of command transmissionmodes.

TABLE 1 Transmission mode DCI format Data transmission scheme tm1 1ASingle antenna transmission, antenna port 0 1 Single antennatransmission, antenna port 0 tm2 1A Transmission diversity 1Transmission diversity tm3 1A Transmission diversity 2A Open-loopspatial multiplexing tm4 DCI format Transmission diversity 1A DCI formatClosed-loop spatial multiplexing & 2 Transmission diversity tm5 DCIformat Transmission diversity 1A DCI format Multi-user MIMO 1D tm6 DCIformat Transmission diversity 1A DCI format Closed-loop spatialmultiplexing 1B (rank-1 limit) tm7 DCI format Transmission diversity 1ADCI format Single antenna transmission, antenna 1 port 5 tm8 DCI formatTransmission diversity 1A DCI format Duplex layer transmission: 2Bantenna port 7 or 8 Single antenna transmission: antenna port 7 or 8 tm9DCI format Transmission diversity 1A

Transmission modes 1 to 6 listed in Table 1 support a referencetransmission scheme based on CRS, whereas transmission modes 7 to 10support a reference transmission scheme based on DRS (antenna port 5) orDM-RS (antenna ports 7, 8, 9, 10, 11, 12, 13, and 14).

The reference transmission scheme based on CRS includes single antennatransmission in a transmitter having only one transmission antenna,transmission diversity for acquiring spatial diversity, open-loopspatial multiplexing performing spatial multiplexing transmissionwithout feedback regarding a spatial channel state, closed-loop spatialmultiplexing performing spatial multiplexing transmission based onfeedback regarding a spatial channel state, multi-user Multiple InputMultiple Output (MIMO) transmitting a plurality of user signals withdifferent shaped beams in the same resource, and closed-loop rank-1pre-coding transmitting a single layer based on feedback regarding aspatial channel state.

Further, the LTE system enables a scheme estimating a channel responseusing a DRS as a common transmission mode, and designates a DRS as an RSfor an antenna port 5, which indicates single antenna transmission, orantenna port 5 scheme.

A transmission mode 8 is added in a Release-9 of the LTE system. Antennaports 7 and 8 being DM-RS are provided, and support spatial multiplexingbased on DM-RS instead of CRS.

Transmission modes 9 and 10 are added in a Release-10 of the LTE-Asystem. In order to support a maximum eight layers of spatialmultiplexing, antenna ports 9, 10, 11, 12, 13, and 14 are defined inadditional DM-RS antenna ports 7 and 8.

For example, the LTE-A system supports transmission modes 1-6 being CRSbased transmission mode, and transmission modes 7-10 being atransmission mode based on DM-RS including DRS.

Each transmitter of the LTE system and the LTE-A system transmits a CRSin all sub-frames. Accordingly, a receiver may receive the CRS from allsub-frames and uses it to estimate a channel of a data signal. However,there is an exception in that a CRS in an MBSFN sub-frame for supportingMBSFN transmission is not transmitted to a data channel region.

The MBSFN transmission scheme spreads a service zone of broadcasting bytransmitting the same broadcasting signal from multiple cells. The MBSFNtransmission regulates to transmit the same RS from the multiple cellssuch that a receiver may perform coherence modulation for thesimultaneously transmitted signals from the transmitter withoutseparation by cells.

Only an MBSFB dedicated RS is defined in the MBSFN sub-frame and istransmitted. Accordingly, when a receiver of the LTE system receives aunicast service, because a CRS in the MBSFN sub-frame is nottransmitted, a data channel signal is not received in the MBSFNsub-frame. For the operation, the transmitter informs the receiver ofthe LTE system having received the unicast service of setting the MBSFNsub-frame through upper signaling, and the receiver previouslyrecognizes which sub-frame is the MBSFN sub-frame.

FIG. 4 illustrates TDD of an MBSFN sub-frame.

Referring to FIG. 4, it is checked whether a normal sub-frame 251 and anMBSFN sub-frame 253 are time-divided. The receiver extracts a CRS fromthe normal sub-frame 251 to estimate a channel of a data signal.Meanwhile, the receiver does not receive a data channel signal from theMBSFN sub-frame 253.

Using the foregoing feature, the LTE-A system may use the MBSFNsub-frame as an optimized resource for the receiver. Because the LTE-Asystem should maintain backward compatibility with the LTE system, atransmitter should always transmit a CRS in a normal sub-frame. However,a receiver of the LTE-A system may set a transmission mode to not referto the CRS in reception of the data channel signal. That is, in areceived mode of the LTE-A system, a resource used in CRS transmissionis discarded. However, because it is expected that a CRS in a datachannel region of the MBSFN sub-frame is not transmitted in the receiverof the LTE system, the receiver of the LTE system recognizes an LTE-Asub-frame as the MBSFN sub-frame, and recognizes an LTE-A sub-frame as asub-frame optimized for the LTE-A system. Since the CRS in the LTE-Asub-frame is not transmitted, the amount of a resource allotted to thedata channel signal may be increased in a side of the receiver of theLTE-A system to increase data transmission efficiency or improve datareception performance.

FIG. 5 illustrates TDD of an LTE-A sub-frame.

Referring to FIG. 5, it is checked whether a normal sub-frame 251 and anLTE-A sub-frame 255 are time-divided. The LTE-A sub-frame is recognizedin a receiver of an LTE system as an MBSFN sub-frame, whereas it isrecognized in a receiver of an LTE-A system as a sub-frame optimized forthe LTE-A system. That is, the transmitter simultaneously transmits aCSR and DM-RS for demodulation of a receiver of the LTE-A system in anormal sub-frame 251 for backward compatibility. However, only DM-RS forthe receiver of the LTE-A system in the data channel region of the LTE-Asub-frame 255 may be transmitted without CRS.

In a DL of the LTE-A system, a transmitter transmits a CRS for thereceiver of the LTE system, and transmits DM-RS for the receiver of theLTE-A system. The DM-RS is a spread DRS to support spatial multiplexing.Because it is assumed that a data signal may configure a maximum ofeight spatial layers, a maximum of eight types of DM-RS are defined sothat a transmitter may apply optional pre-coding. If the pre-coding islimited to a pre-coding codebook, it is not suitable to a multi-userMIMO, and a DCT for supporting Coordinated Multi-Point (CoMP) JointTransmission (JT) becomes significantly complicated. To efficientlysupport a transmission scheme to be newly introduced in the LTE-Asystem, a new DM-RS is introduced instead of reusing the CRS.

However, in a normal sub-frame, the transmitter should transmit a CRSfor a receiver of an LTE system and DM-RS for an LTE-A system,respectively. Although a transmission scheme of an LTE-A system usingDM-RS is efficient, if two types of RS are always transmitted, a largeamount of resources may be unnecessarily consumed in the RS. For thisreason, lower data transmission rate may be obtained in a transmissionscheme of an LTE-A system using DM-RS in comparison with that of the LTEsystem. Accordingly, a receiver of the LTE-A system may receive a datasignal selectively using a CRS as in the receiver of the LTE system toimprove a data transmission rate.

To set a transmission mode using a multiple transmission antenna in a DLof the LTE system, upper signaling as illustrated in Table 2 below isdefined. That is, the upper signaling includes a situation informationelement for informing a multiple transmission antenna relation situationfor each receiver, and for example, may be defined as‘AntennaInfoDedicated’ including a mode information element for defininga transmission mode of the LTE system. The mode information element maybe defined as ‘transmissionMode’, and informs which transmission mode isset as 3 bit information. If the mode information element‘transmissionMode’ is set to tmA, it indicates that the mode informationelement ‘transmissionMode’ is set as a transmission mode A. For example,if tm3 is set, it indicates that a transmission mode 3 is set.

TABLE 2 AntennaInfoDedicated :: = SEQUENCE {  transmissionMode ENUMERATED { tm1, tm2, tm3, tm4, tm6, tm7, tm8},  the remainder isomitted }

Transmission modes 9 and 10 are added in a DL of the LTE-A system.Accordingly, the transmission mode may not be set with‘AntennaInfoDedicated’ as illustrated in Table 2. As a result, thereceiver of the LTE-A system receives upper signaling of‘AntennaInfoDedicated-rel10’ to be described later to recognize thetransmission mode.

A first embodiment of the present invention defines both of modeinformation elements ‘transmissionMode-rel10’ and ‘transmissionModeMBSFN-rel10’ as illustrated in Table 3 below. The mode informationelement ‘transmissionMode-rel10’ is for informing which transmissionmode is set in a general situation applicable to both a normal sub-frameand an LTE-A sub-frame. If one of transmission modes 7, 8, 9, and 10 isset, it performs as a DM-RS based transmission mode in all sub-frames.However, when one of the transmission modes 1, 2, 3, 4, 5, and 6 is set,the set mode corresponds to a CRS based transmission mode, which is notapplicable to an LTE-A sub-frame but is applicable to only a normalsub-frame to which a CRS is transmitted. That is, a receiver set in theCRS based transmission mode may not receive a data channel signal fromthe LTE-A sub-frame.

To solve the problem, a mode information element of‘transmissionModeMBSFN-rel10’ is additionally defined, and is configuredwith 4-bits indicating in which transmission mode a receiver of an LTE-Asystem is set in the LTE-A sub-frame. Because a CRS in the LTE-Asub-frame is not transmitted, one of transmission modes 7, 8, 9, and 10being a DM-RS based transmission mode is selected.

TABLE 3 AntennaInfoDedicated-re110 :: =  SEQUENCE { TransmissionMode-re110   ENUMERATED {  tm1, tm2, tm3, tm4, tm6, tm7, tm8, tm9, tm10, reserved1, reserved2, reserved3, reserved4, reserved5,reserved6,},  transmissionModeMBSFN-rel10 ENUMERATED {    tm7, tm8, tm9,tm10},  the remainder is omitted }

A second embodiment of the present invention always defines a modeinformation element ‘transmissionMode-rel10’ as illustrated in Table 4below. However, to maintain a transmission mode indicated by a modeinformation element ‘transmissionMode-rel10’ in an LTE-A sub-frame, atransmitter of an LTE-A system may omit the mode information element‘transmissionModeMBSFN-rel10’. Table 4 indicates a structure of uppersignaling of ‘AntennaInfoDedicated-rel10’ for supporting thisembodiment. In contrast with the first embodiment,‘transmissionModeMBSFN-rel10’ is selectively set by a transmitter. Whena receiver of an LTE-A system is set in a DM-RS based transmission modeby ‘transmissionMode-rel10’ but ‘transmissionModeMBSFN-rel10’ is notset, it regards as a DM-RS based transmission mode set by‘transmissionMode-rel10’ in an LTE-A sub-frame and receives a datachannel signal.

TABLE 4 AntennaInfoDedicated-re110 :: =  SEQUENCE { TransmissionMode-re110   ENUMERATED {  tm1, tm2, tm3, tm4, tm6, tm7, tm8, tm9, tm10, reserved1, reserved2, reserved3, reserved4, reserved5,reserved6,},  transmissionModeMBSFN-rel10 ENUMERATED {  tm7, tm8, tm9,tm10} OPTIONAL,  the remainder is omitted }

A third embodiment of the present invention does not support atransmission mode 7 being a DRS based transmission mode in a modeinformation element ‘transmissionModeMBSFN-rel10’, but instead supportsonly transmission modes 8, 9, and 10 as illustrated in Table 5 below.That is, only one of the transmission modes 8, 9, and 10 is set in theLTE-A sub-frame. Table 5 is a structure of upper signaling of‘AntennaInfoDedicated-rel10’ for supporting this embodiment.

TABLE 5 AntennaInfoDedicated-re110 :: =  SEQUENCE {  TransmissionMode-re110   ENUMERATED {  tm1, tm2, tm3, tm4, tm6, tm7, tm8, tm9, tm10, reserved1, reserved2, reserved3, reserved4, reserved5,reserved6,},  transmissionModeMBSFN-rel10 ENUMERATED {    tm8, tm9,tm10, reserved},   the remainder is omitted }

A fourth embodiment of the present invention does not supporttransmission modes 7 and 8 being DRS or DM-RS based transmission modedefined in LTE Release-8 and Release-9 of a mode information element‘transmissionModeMBSFN-rel10’ but supports transmission modes 9 and 10newly added in an LTE-A as illustrated in Table 6 below. That is, onlyone of transmission modes 9 and 10 is set in the LTE-A sub-frame. Table6 indicates a structure of upper signaling of‘AntennaInfoDedicated-rel10’ for supporting this embodiment. The‘transmissionModeMBSFN-rel10’ is 1-bit information in this embodiment.

TABLE 6 AntennaInfoDedicated-re110 :: =  SEQUENCE { TransmissionMode-re110   ENUMERATED {  tm1, tm2, tm3, tm4, tm6, tm7, tm8, tm9, tm10, reserved1, reserved2, reserved3, reserved4, reserved5,reserved6,},  transrnissionModeMBSFN-rel10 ENUMERATED {    tm9, tm10,reserved},  the remainder is omitted }

A fifth embodiment of the present invention may set all transmissionmodes with ‘transmissionModeMBSFN-rel10’ as illustrated in Table 7below. If one of transmission modes 1, 2, 3, 4, 5, and 6 being a CRSbased transmission mode is set in a mode information element‘transmissionModeMBSFN-rel10’, a receiver estimates a channel using aCRS which is absent in a data region of an LTE-A sub-frame, but ispresent in a control channel and a peripheral sub-frame and receives adata channel signal transmitted in a CRS based transmission scheme.

TABLE 7 AntennaInfoDedicated-re110 :: =  SEQUENCE { TransmissionMode-re110   ENUMERATED {  tm1, tm2, tm3, tm4, tm6, tm7, tm8, tm9, tm10, reserved1, reserved2, reserved3, reserved4, reserved5,reserved6,},  transmissionModeMBSFN-rel10 ENUMERATED {  tm1, tm2, tm3,tm4, tm6, tm7,  tm8, tm9, tm10, reserved1, reserved2, reserved3,reserved4, reserved5, reserved6,},  the remainder is omitted }

FIG. 6 illustrates a structure of a transmitter according to the presentinvention. In FIG. 6, the transmitter includes two transmissionantennae. However, the present invention is not limited thereto. Thatis, the same explanations are applicable to when the transmitterincludes more than two transmission antennae.

Referring to FIG. 6, a transmitter 300 includes a transmissioncontroller 301, a first multiplexer 304, a first pre-coder 309, a secondpre-coder 313, a second multiplexer 315 a, a third multiplexer 315 b, afirst transmission antenna 317 a, and a second transmission antenna 317b. The transmitter 300 multiplexes data signals 303 according to a DM-RS305 or a CRS 311, and transmits the multiplexed signal. In an LTE-Asub-frame, the transmitter 300 transmits a DM-RS 305 but does nottransmit a CRS 311 in a data region. In a normal sub-frame, thetransmitter 300 transmits a CRS 311 to maintain backward compatibility,and additionally transmits a DM-RS 305, if necessary, according to atransmission mode set in a receiver of an LTE-A system.

The transmission controller 301 determines which of an LTE-A sub-frameor a normal sub-frame is a current sub-frame. If the current sub-frameis the LTE-A sub-frame, the transmission controller 301 performs acontrol operation to generate and transmit data signals 303 and a DM-RS305. In this case, the transmission controller 301 determines a DCIformat with reference to a transmission mode for an LTE-A sub-frame setin a scheduled receiver. The number of DM-RSs 305 is determinedaccording to the number of spatial multiplexing layers, and is reportedto a receiver through a DCI transmitted with PDCCH.

If the current sub-frame is the normal sub-frame, the transmissioncontroller 301 performs a control operation to generate and transmit thedata signals 303 and the CRS 311, and a DM-RS 305, if necessary,according to the transmission mode set in a receiver of the LTE-Asystem. In this case, the transmission controller 301 determines a DCIformat with respect to a general transmission mode set in a scheduledreceiver. In a CRS based transmission mode, the DM-RS 305 is nottransmitted, and pre-coding information used when a transmittertransmits a data channel signal is reported through a DCI or is regardedby a preset transmission mode. The number of DM-RSs 305 is determined bythe number of spatial multiplexing layers, and is reported to a receiverthrough the DCI transmitted with the PDCCH.

When the data signals 303 and the DM-RS 305 are input to the firstmultiplexer 307, it multiplexes the data signals 303 according to theDM-RS 305 and transfers the multiplexed signal to the first pre-coder309, which applies the same pre-coding to the data signals 303 and theDM-RS 305. When the data inputs 300 are input to the first multiplexer307 without the DM-RS 305, it multiplexes the data signals 300 andtransfers the multiplexed signal to the first pre-coder 309, which alsopre-codes the data signal 303. In the case, the transmission controller301 determines which pre-coding is applied for a specific receiver inthe first pre-coder 309.

When a CRS 311 is input to the second pre-coder 313, it applies a fixedpre-coding to the CRS 311. The fixed pre-coding indicates thatpre-coding remains the same and is not changed according to a channelstate of a receiver. The fixed pre-coding is applied because a rulearranging a maximum of four CRSs of an LTE system in maximumtransmission antennae should be applied, since a receiver of an LTEsystem recognizes that an LTE-A system has a maximum of fourtransmission antennae although an LTE-A system may include up to eighttransmission antennae. Such a procedure is referred to as antennavirtualization. In this case, the pre-coder 313 determines how toarrange the CRS in the first transmission antenna 317 a and the secondtransmission antenna 317 b.

When the data signal 303 and the DM-RS 305 pre-coded from the firstpre-coder 309 are input to the second multiplexer 315 a and the thirdmultiplexer 315 b, they multiplex the data signals 330 according to theDM-RS 305 and transmit the multiplexed signal through the firsttransmission antenna 317 a and the second transmission antenna 317 b.When the pre-decoded data signal 303 from the first pre-coder 309 andthe pre-coded CRS 311 from the second pre-coder 313 are input to thesecond multiplexer 315 a and the third multiplexer 315 b, they multiplexthe pre-decoded data signal 303 according to the CRS 311 and transmitthe multiplexed signals through the first transmission antenna 317 a andthe second transmission antenna 317 b, respectively.

FIG. 7 illustrates a structure of a receiver according to the presentinvention. In FIG. 7, the receiver includes two receiving antennae.However, the present invention is not limited thereto. That is, the sameexplanations are applicable to when the receiver includes more than tworeceiving antennae.

Referring to FIG. 7, a receiver 400 includes a receiving controller 401,a first receiving antenna 403 a, a second receiving antenna 403 b, afirst demultiplexer (DEMUX) 405 a, a second demultiplexer 405 b, achannel estimator 407, a combiner 409, and a data processor 413.

The receiving controller 401 analyzes upper signaling to determine whichof an LTE-A sub-frame or a normal sub-frame is a current sub-frame, anddetermines the following with reference to a transmission mode set in areceiver and control information DCI provided through PDCCH.

The receiving controller 401 determines:

-   -   i. whether an RS to be used in channel estimation for        demodulation is CRS or DM-RS (according to a transmission mode        previously set through upper signal);    -   ii. how many DM-RSs should be estimated when the DM-RS is used        for channel estimation of demodulation (based on DCI provided        through PDCCH);    -   iii. which format DCI including a data receiving method and        resource allot information is assumed to receive PDCCH (based on        a transmission mode previously set by upper signaling); and    -   iv. in which resource the data channel signal is received (based        on DCI transmitted through PDCCH).

When the first receiving antenna 403 a and the second receiving antenna403 b receive signals, the first demultiplexer 405 a and the seconddemultiplexer 405 b demultiplex the signals to divide the signals intoan RS and data signals. In this case, the first demultiplexer 405 a andthe second demultiplexer 405 b transfer the RS to the channel estimator407, and transfer the data signals to the combiner 409.

The channel estimator 407 estimates a channel using an input RS. Whenthe receiving controller 401 determines whether the current sub-frame isthe LTE-A sub-frame, the channel estimator 407 receives a PDCCHaccording to a transmission mode for the LTE-A sub-frame, and acquiresDCI information and determines which RS will be used to estimate achannel. The receiving controller 402 instructs the channel estimator407 to estimate a channel necessary for demodulation. However, if thetransmission mode for the LTE-A sub-frame is not set or is set as a CRSbased transmission mode, the receiving controller 401 determines that adata channel signal in the LTE-A sub-frame is not transmitted andterminates a receiving procedure of the data channel signal. However,when a transmitter sets by force to receive a data channel signal fromthe LTE-A sub-frame using a CRS included in a control channel region anda peripheral sub-frame, the receiving controller 401 instructs thechannel estimator 407 to estimate a channel using the CRS included inthe control channel region and the peripheral sub-frame.

When it is determined that a current sub-frame is a normal sub-frame,the receiving controller 401 receives data signals and estimates achannel according to a transmission mode set in a mode informationelement “transmissionMode-rel10”. That is, when a CRS based transmissionmode is set in the “transmission Mode-rel10”, the receiving controller401 receives a PDCCH according to a corresponding transmission mode toacquire DIC information, and instructs the channel estimator 407 toestimate a channel necessary for demodulating a data channel signalusing the CRS. If a DM-RS based transmission mode is set in“transmissionMode-rel10”, the receiving controller 401 receives a PDCCHaccording to a corresponding transmission mode to acquire DCIinformation, and instructs a channel estimator 407 to estimate a channelnecessary for demodulating a data channel signal using a DM-RS.

The channel estimator 407 applies a channel estimating method accordingto a pattern of an RS indicated by the receiving controller 401 toestimate a channel, and transfers the estimated channel to the receivingcontroller 401. Through this, the receiving controller 401 determines acombining coefficient indicating the manner in which data signalsreceived by the first receiving antenna 403 a and the second receivingantenna 403 b are to be combined. The receiving controller 401 transfersthe combining coefficient to the combiner 409.

The data signals and the combining coefficient are input to the combiner409, which suitably combines the data signals according to the combiningcoefficient to obtain a restored data symbol 411. The data processor 413demodulates and decodes the data symbol 411 to restore an informationbit row. In this case, the data processor 413 may perform suitabledemodulation and decoding according to transfer of a modulation andcoding method reported with a DCI from the receiving controller 401.

A procedure for receiving a data channel signal in a data channel regionby a receiver will be described in detail.

FIG. 8 illustrates a method for using a reference signal by a receiveraccording to a first, third, or fourth embodiment of the presentinvention.

Referring to FIG. 8, a receiver of an LTE-A system determines modeinformation elements, namely, “transmission Mode-rel10” and“transmissionModeMBSFN-rel10” from a situation information element ofupper signaling, namely, “AntennaInfoDedicated-rel10” (501). Thereceiver may recognize a transmission mode set in a receivercorresponding to a current sub-frame, and may recognize a transmissionmode set in a corresponding receiver from transmission modes 1 to 10 inTable 1 based on a mode information element. The receiver determineswhether a current sub-frame is an LTE-A sub-frame (503).

If the current sub-frame is a normal sub-frame, the receiver assumes anormal sub-frame mode set in “transmissionMode-rel10” to receive a datachannel signal (505). In this case, the receiver may receive the datachannel signal according to one of transmission modes 1 to 10 inTable 1. Conversely, if the current sub-frame is the LTE-A sub-frame,the receiver assumes an LTE-A sub-frame transmission mode set in“transmissionModeMBSFN-rel10” to receive the data channel signal (507).The receiver may receive the data channel signal according to one oftransmission modes 7 to 10 in Table 1.

FIG. 9 illustrates a method for using a reference signal by a receiveraccording to a second embodiment of the present invention.

Referring to FIG. 9, a receiver of an LTE-A system determines modeinformation elements, namely, “transmissionMode-rel10” and“transmissionModeMBSFN-rel10” from a situation information element ofupper signaling, namely, “AntennaInfoDedicated-rel10” in step 601. Thereceiver may recognize a transmission mode set in a receivercorresponding to a current sub-frame, and may recognize a transmissionmode set in a corresponding receiver from transmission modes 1 to 10 inTable 1 based on a mode information element. The receiver determineswhether a current sub-frame is an LTE-A sub-frame in step 603.

If the current sub-frame is a normal sub-frame, the receiver assumes anormal sub-frame set in “transmissionMode-rel10” to receive a datachannel signal in step 605. The receiver may receive the data channelsignal according to one of transmission modes 1 to 10 in Table 1.Conversely, if the current sub-frame is the LTE-A sub-frame, thereceiver 611 checks “transmissionModeMBSFN-rel10” to determine whether atransmission mode for the LTE-A sub-frame is set in step 611. If thetransmission mode for the LTE-A sub-frame is set, the receiver assumesan LTE-A sub-frame transmission mode set in“transmissionModeMBSFN-rel10” to receive the data channel signal in step613. If the transmission mode for the LTE-A sub-frame is not set, thereceiver determines whether a normal sub-frame transmission mode set in“transmissionMode-rel10” is based on a CRS in step 615. If the normalsub-frame transmission mode is based on the CRS, because there is no CRSin the LTE-A sub-frame, a base station stops reception of the datachannel signal in step 617. If the normal sub-frame transmission mode isbased on a DM-RS, because the DM-RS may be transferred to the LTE-Asub-frame, a base station assumes a normal sub-frame transmission modeset in “transmissionMode-rel10” to receive the data channel signal instep 605.

FIG. 10 illustrates a method for using a reference signal by a receiveraccording to a fifth embodiment of the present invention.

Referring to FIG. 10, a receiver of an LTE-A system determines modeinformation elements, namely, “transmission Mode-rel10” and“transmissionModeMBSFN-rel10” from a situation information element ofupper signaling, namely, “AntennaInfoDedicated-rel10” in step 701. Thereceiver may recognize a transmission mode set in a receivercorresponding to a current sub-frame, and may recognize a transmissionmode set in a corresponding received from transmission modes 1 to 10 inTable 1 based on a mode information element. The receiver determineswhether a current sub-frame is an LTE-A sub-frame in step 703.

If the current sub-frame is a normal sub-frame, the receiver assumes anormal sub-frame transmission mode set in “transmissionMode-rel10” toreceive a data channel signal in step 705. The receiver may receive thedata channel signal according to one of transmission modes 1 to 10 inTable 1. Conversely, if the current sub-frame is the LTE-A sub-frame,the receiver 611 checks “transmissionModeMBSFN-rel10” to determinewhether a transmission mode set for the LTE-A sub-frame is based on aCRS in step 721. If the transmission mode set for the LTE-A sub-frame isbased on the CRS, the receiver assumes an LTE-A sub-frame transmissionmode set in “transmissionModeMBSFN-rel10” to estimate a channel and toreceive a data channel signal using a CRS of a control channel region inthe LTE-A sub-frame and a CRS of a peripheral sub-frame in step 723.

The receiver may receive a data channel signal according to one oftransmission modes 1 to 6 in Table 1. If the transmission mode for theLTE-A sub-frame is based on the DM-RS or the DRS, the receiver assumesan LTE-A sub-frame transmission mode set in“transmissionModeMBSFN-rel10” to receive the data channel signal in step725. The receiver may receive the data channel signal according to oneof transmission modes 7 to 10 in Table 1.

Although embodiments of the present invention have been described indetail hereinabove, it should be clearly understood that many variationsand modifications of the basic inventive concepts herein taught whichmay appear to those skilled in the present art will still fall withinthe spirit and scope of the present invention, as defined in theappended claims.

What is claimed is:
 1. A method for receiving data at a User Equipment(UE) from a base station in an LTE Advance (LTE-A) communication system,the method comprising: receiving information for at least onetransmission mode among multiple transmission modes from the basestation through higher layer signaling, wherein the at least onetransmission mode includes at least one of transmission mode 9 (tm9) andtransmission mode 10 (tm10); receiving information for a MultimediaBroadcast Multicast Service Single Frequency Network (MBSFN) sub-framefrom the base station through the higher layer signaling; receivingDownlink Control Information (DCI) for a data signal, wherein a formatof the DCI for the data signal is DCI format 1A; determining atransmission scheme corresponding to a current sub-frame based on theinformation for the transmission mode, the information for the MBSFNsub-frame, and the format of the DCI for the data signal; and processingthe data signal based on the transmission scheme.
 2. The method of claim1, wherein at least one of the multiple transmission modes is based on aCommon Reference Signal (CRS) and at least one of the multipletransmission modes is based on a Demodulation Reference Signal (DM-RS).3. The method of claim 2, further comprising: when the current sub-frameis the MB SFN sub-frame, receiving the data signal based on at least onetransmission mode for the MB SFN sub-frame; and when the currentsub-frame is a normal sub-frame, receiving the data signal according toat least one transmission mode for the normal sub-frame.
 4. The methodof claim 1, wherein the format of the DCI includes information for aDemodulation-Reference Signal (DM-RS).
 5. A method for transmitting dataat a Base Station (BS) in an LTE Advance (LTE-A) communication system,the method comprising: transmitting information for at least onetransmission mode among multiple transmission modes to a User Equipment(UE) through higher layer signaling, wherein the at least onetransmission mode includes at least one of transmission mode 9 (tm9) andtransmission mode 10 (tm10); transmitting information for a MultimediaBroadcast Multicast Service Single Frequency Network (MBSFN) sub-frameto the UE through the higher layer signaling; transmitting DownlinkControl Information (DCI) for a data signal, wherein a format of the DCIfor the data signal is DCI format 1A; determining a transmission schemecorresponding to a current sub-frame based on the information for thetransmission mode, the information for the MBSFN sub-frame, and theformat of the DCI for the data signal; and transmitting the data signalbased on the transmission scheme.
 6. The method of claim 5, wherein atleast one of the multiple transmission modes is based on a CommonReference Signal (CRS) and at least one of the multiple transmissionmodes is based on a Demodulation Reference Signal (DM-RS).
 7. The methodof claim 5, wherein the format of the DCI includes information for aDemodulation-Reference Signal (DM-RS).
 8. An apparatus for receivingdata from a base station in an LTE Advance (LTE-A) communication system,the apparatus comprising a receiving controller and a data processor,the receiving controller and data processor configured to: receive, bythe receiving controller, information for at least one transmission modeamong multiple transmission modes from the base station through higherlayer signaling, wherein the at least one transmission mode includes atleast one of transmission mode 9 (tm9) and transmission mode 10 (tm10);receive, by the receiving controller, information for a MultimediaBroadcast Multicast Service Single Frequency Network (MBSFN) sub-framefrom the base station through the higher layer signaling; receive, bythe receiving controller, Downlink Control Information (DCI) for a datasignal, wherein a format of the DCI for the data signal is DCI format1A; determine, by the receiving controller, a transmission schemecorresponding to a current sub-frame based on the information for thetransmission mode, the information for the MBSFN sub-frame, and theformat of the DCI for the data signal; and process, by the dataprocessor, the data signal based on the transmission scheme.
 9. Theapparatus of claim 8, wherein at least one of the multiple transmissionmodes is based on a Common Reference Signal (CRS) and at least one ofthe multiple transmission modes is based on a Demodulation ReferenceSignal (DM-RS).
 10. The apparatus of claim 9, wherein the receivingcontroller is further configured to: when the current sub-frame is theMBSFN sub-frame, receive the data signal based on at least onetransmission mode for the MBSFN sub-frame; and when the currentsub-frame is a normal sub-frame, receive the data signal based on atleast one transmission mode for the normal sub-frame.
 11. The method ofclaim 8, wherein the format of the DCI includes information for aDemodulation-Reference Signal (DM-RS).
 12. An apparatus for transmittingdata in an LTE Advance (LTE-A) communication system, the apparatuscomprising a transmission controller and a multiplexer, the transmissioncontroller and the multiplexer configured to: transmit, by thetransmission controller, information for at least one transmission modeamong multiple transmission modes to a User Equipment (UE) throughhigher layer signaling, wherein the at least one transmission modeincludes at least one of transmission mode 9 (tm9) and transmission mode10 (tm10); transmit, by the transmission controller, information for aMultimedia Broadcast Multicast Service Single Frequency Network (MBSFN)sub-frame to the UE through the higher layer signaling; transmitDownlink Control Information (DCI) for a data signal, wherein a formatof the DCI for the data signal is DCI format 1A; determine, by thetransmission controller, a transmission scheme corresponding to acurrent sub-frame based on the information for the transmission mode,the information for the MBSFN sub-frame, and the format of the DCI forthe data signal; and transmit, by the transmission controller, the datasignal based on the transmission scheme.
 13. The apparatus of claim 12,wherein at least one of the multiple transmission modes is based on aCommon Reference Signal (CRS) and at least one of the multipletransmission modes is based on a Demodulation Reference Signal (DM-RS).14. The method of claim 12, wherein the format of the DCI includesinformation for a Demodulation-Reference Signal (DM-RS).